Breech bolt and retracting means therefor



Nov. 11, 1947. R. 1.. JENKINSON BREECH BOLT AND RETRACTING MEANS THEREFOR 2 Sheets-Sheet 1 Filed Sept. 4, 1944 Nov. 11, 1947. R. L. JENKINSON BREECH BOLT AND RETRACTING MEANS THEREFOR Filed Sept. 4, 1944 2 Sheets-Sheet 2 Patented Nov. 11, 1947 BREECH BOLT AND RETRACTING IWEAN S THEREFOR Robert L. Jenkinson, Teaneck, N. J., assignor to The Marlin Firearms Company, New Haven, Conn., a corporation of Connecticut Application September 4, 1944, Serial No. 552,639

4 Claims. 1

This invention relates to firearms, and more particularly to a firearm of the semi-automatic type. As shown, it is applied to a semi-automatic bolt-action rifle, although it will be understood that in certain of its aspects the invention is applicable to other types of firearms.

Distinction is usually made between an automatic firearm and one of the semi-automatic type, in that a fully automatic gun continues to fire as long as the trigger is held back, while in the semi-automatic type of gun the trigger must be released and pulled again for each successive discharge, although the loading and cooking of the gun are effected automatically.

In a gun of this type it is necessary that the introduction of the new cartridge into the chamber from the magazine be accomplished with smoothness and ease, for, as will be obvious, the movement of the bolt takes place very rapidly upon the discharge of the gun. It is, therefore, contemplated by the present invention to provide a new and improved carrier to move a fresh cartridge from the magazine into a position to be forced into the barrel by the return of the bolt. Also it is desirable in guns of this type, and particularly in a gun adapted for civilian use, to provide for a ready conversion of the gun from one of the semi-automatic type to one of the manual or single-shot type, wherein the loading and cocking operations are effected manually.

In bolt-action guns it is more or less usual to provide a threaded plug or bumper at the rear of the receiver, against which the bolt and striker springs react. When it is desired to remove the bolt and other parts of the action from the receiver, this plug is unscrewed and the parts are removed. The parts, however, become disassembled to some extent in such an operation, and are difiicult of reassembly and replacement into the receiver due to the fact that the springs must be compressed to some extent in this operation. In the present invention the receiver plug or bumper is held in place by a bayonet joint, and means are provided for locking the bolt to this bumper when it is desired to remove the bolt and associated parts from the receiver, so that the bolt and bumper may be removed in assembled position so that the tension of the springs does not have to be released.

7 One object of the present invention is to provide a new and improved firearm of the semiautomatic type.

Still another object of the invention is to provide a bolt-action firearm wherein the bolt and associated parts may be readily removed from the receiver and replaced therein.

A still further object of the invention is to provide a firearm of the semi-automatic type, which may be readily converted into a manually operated bolt-action single-shot firearm.

Still another object of the invention is the improvement of the loading mechanism of an automatic firearm, which mechanism serves to transfer a fresh cartridge from the magazine into a position to be inserted into the chamber upon the return of the bolt.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a side elevational view of the receiver portion of a firearm embodying my invention;

Fig. 2 is a longitudinal sectional view of the parts shown in Fig. 1;

Fig. 3 is a fragmentary sectional view similar to Fig. 2, but showing the cartridge carrier in another position;

Fig. 4 is a view similar to Fig. 3, showing still another position of the parts when a fresh cartridge is about to be inserted into the chamber;

Fig. 5 is a ectional view on line 55 of Fig. 2;

Fig. 6 is a side elevational view, partly in sec tion, of the rear end of the receiver, showing the provision for coupling together the bolt and the receiver plug or bumper;

Fig. 7 is a sectional view on line 'l'l of Fig. 6;

Fig. 3 is a side elevational view of the rear end of the receiver from a slightly difierent angle from that shown in Fig. 1;

Fig 9 is an exploded View of the receiver bumper and bolt, the latter being shown in section;

Fig. 10 is a detail view of the cartridge carrier;

Fig. 11 is .a top plan view of the carrier shown in Fig. 10;

Fig. 12 is an enlarged view of the bolt handle and associated structure, certain parts being shown in section for the sake of clearness; and

Fig 13 is a side elevational view of the bolt handle.

To illustrate a preferred embodiment of my invention I have shown my improvements as applied to a repeating rifle having a barrel l0, magazine II and receiver l2, a cartridge l3 being shown in Fig. 2 in the chamber I4.

Within the receiver is mounted a bolt l5 designed to be retracted by the recoil from the firing of the cartridge, the bolt having slidably mounted therein a firing pin [6 (Fig. 9) adapted to be actuated by a striker l1, also slidably associated with the bolt. A bolt spring l8 serves to urge the bolt forwardly, this spring being disposed within a recess in the bolt and surrounding a pin [9 secured to a disk-like member 26. Also secured to the member 20 is a pin 2| surrounded by a striker spring 22 disposed within a recess or. opening in the striker ll.

As shown in Fig. 6, the member 29, against which the springs I8 and 22 react, abuts against a bumper or plug 24 which closes the rear end of the receiver. This bumper is held in' place by a screw 25 (Fig. '7) which is rotatably mounted' in" the bumper and threaded into-an. opening in the receiver, as shown at 2B. The screw: 25 is; also capable of movement in the direction ofitslength' in the bumper, but is prevented from being removed entirely by a collar 2''! on' the screw which bears against the bottom shoulder 28 of: an en larged recess 29 forming a continuation of the opening. in the bumper 2 3. inwhich the screw is disposed.

The portion of the screw adjacent the-head 38' projects through the. receiver and is received in. an L-shaped slot 31' (Fig. 8) ,thus forming abayonet joint between these two parts. It. will be obvious that when the screw is in the. position shown in Fig. 7, in which it is. threadedly en.- gaged with the receiver at 26., the. bumper. is. locked to the receiver. However,.when\the screw hasv been backed 01f sufiiciently. to disengage: itsthreads from the receiver, it may be-given a slightmovement of rotation inthelateral or circumferential portion. of the slot. 3|, and then,.by a longi@-- tudinal movement, thev bumper. may-bewithdrawn from the receiver.

As shown more especially inFig-s. 6. and 9-, the bumper is provided with a pair of prongs; or

fingers 32 each having a hook-shaped end: 33..

Each of these prongs is adapteditofbereceived:inan L-shaped slot in the bolt, this-'slothaving' a longitudinal or axial portion-6 L and a: transverse or circumferential portion 35. In thev normalpo sition of the parts shown in- Figs.- 6; 7: and 8, the fingers 32* are not in locked engagement with the bolt, but slide freely through the-longitudinalportion 3 of the slot in-t-he bolt, so that the-bolt has free reciprocating movement in the operation of the gun. However, when the screw 25; is disena gaged from the receiver and: given azpartialzrotary motion as permitted by the li-shaped slot 31 thehooked ends 33 of the fingers 32- engaget-he shoulder 36 or the circumferentialportioniofi the slot. in the bolt and lock the bolt and bumper together- At this time, as will be presentlyexplained, the bumper, together wtih the bolt and; associated parts, may be freely withdrawn fromthe receiver; It will be understood that at this time the" disk 20 will be clamped between the bumper andsprings so that this withdrawal will notbe affected by the tension of the springs I8 and" 22;. the tension of which will be carriedbythe; locked engagement ofthe bumper and bolt. so. that the entire bolt mechanism: will be withdrawn; as.= a. unit.

The bolt handle mechanism is shown more especially in Figs; 5, l2 and 1-3,. and comprises a cylindrical post or plug 33 havingra-t. its. innerrend a reduced portion 39 freely'socketed nnarecess49- in the bolt. The sides of the memberi38 are fiat tened or cut away' adjacent: its outer 'end', as shownat 41, to provide a reduced neck: portion which slides in. the slot 42 in the receiven. the

shoulders 6'3 beyond. these cut-away ptortion's'emaguide lug. 5H;

4 handle in place and engaged with the bolt, and the engagement of the reduced neck portion of the member 38 prevents any rotary movement of the bolt in the receiver.

Pivoted to the member 38 on a pin 44 is the bolt handle 45, this handle being provided with a stem 46. received Within a slot 41 inthe member 38, and. a spring-pressed plunger 48 engages the inner surface of the stem to releasably hold the handle in a predetermined position. The width of the body of the stem 46 is substantially that of theslot 42"; but" at its inner end the stem is somewhat enlarged laterally or circumferentially of thereceiver to provide a locking lug 49 and Also provided on the handle 45 oppositethelug:49;is a second locking lug 5i, and, asshown in Figs. 1 and 6, the longitudinal slot 42 in the receiver in which the bolt handle slides is providediwith laterally extending recesses 53 and 54 adjacent its front end, similarly arranged recesses 55 and. 56.. adjacent. its rear end, and an openingof keyholeshapefil at. its rear end-.-

As shown in Fig. 5,.thehandle 45 may be swung.

through. a small angle about the pivot pin 4'4. When the handle stands in. the. full-line positionshown in Fig- 5., the. gun. will operate as a semiautomatic gun, as the bolt will be. freeto: move rearwardly under. the. impulse ofthe. recoil due to. the. discharge of the cartridge. If, however, it.is not desired to-have automaticoperation, butv touse thegun as a single-shotfirearm,,the handle 45. is moved. to the dotted-line position shown in thisfigure. Thiseffects engagement of the looking lug 49 in the recess53- at theforward end of the slot t2, and also. engagement. ofthe locking log 51. in the recess 54,. and prevents the bolt being moved-backby the force ofthe. recoil. The: operator may. after discharge. of the gun, swing the handle45 to-its full -lineposition, and there after retract the bolt by means of the handle,. thus throwing. anew cartridgeinto the. chamber. andcocking the gun.

To-remove the bolt.- and. associated mechanism: from the receiver, the'operatormoves the handle 45 andbolt rearwardly to the position shown in. Fig. 6, and: then. swings the handle through. a slight angle. about its pivot-toeng-age the locking. lugs 4Q and-5|. in the recesses 55 and\56,.and-thus-. prevent. the.:return..of thebolt-by itsspring- The. bolt iSE now in position shown. in Fig..- 6', wherein. the hooked ends. 33wregister. withthe. circumferential. portion 35. of. the bolt. s-lot. Ifv now. the. screw 25 isloosened andthe bumper. 24 given a.-slightturn,, the. hooked ends 33- of. the' fingers 3.2. willengage the. shoulders. 36 of the slot portions 35 and lockthe: bumper. and bolt togethen. 'I-hus thereturn of the. bolt-will now. be prevented because. it. is locked. tothe. bumper, and. the handle:

45- may-bedisengagedfr-om the slots-55 and 56.

Normally thebolt-is never retracted to a greater extent. than. shown in Fig- 6,. as in this position it. is against the. disk. Z'iLwhich in. turn is. against. the bumper 25. However, when the bumper is rotated through a slot angle to bring the. fingers 32' into engagement with the shoulders 36, the screw 26' is moved into the longitudinal portion ofthe' slot 3|, thus permitting the bumper to be moved longitudinally'out of the receiver; There fore, thebolt may now be movedaslight distance rearwardly by the handle b from the position shown in Fig; 6; until thepos-t 38 0f the handle stands inthe keyhole-shaped portion 51 of the" slot 42. This permits the entire handle mecha-- nism; shownin- Fig; lfiifor example; to be withdrawnfreelyfrom the bolt; sothat-the bolt and bumper assembly are loose in the receiver and may be freely withdrawn as a unit, the parts being held together by the engagement of the hooked ends 33 of the fingers 32 in the slots 35, with the springs compressed between these two parts. The parts may, of course, be reassembled by reversing the process just described, and it will be obvious that this provides an easy and convenient way for removing the operating parts from the receiver when such is desired. It will also be understood that normally the handle 45 cannot be disengaged from the bolt due to the fact that the body portion of the post 38 is larger than the slot 42, and the shoulders below the flattened portion GI prevent the handle being removed through this slot; The recesses 53, 5G; 55 and 56 merely permit the swinging of the handle member 45 from full to dotted-line position shown in Fig. 5, but do not permit the withdrawal of the post 38 therethrough. The lower end of the stem 56 is provided with recesses 59 and 68 to receive the plunger .8, and thus releasably hold the handle in either its full or dotted-line position.

At the rear of the magazine H, a carrier or cradle 62 is pivotally attached to the receiver at 63. This carrier is shown more especially in Fig. 11, and is provided with a hollow body portion 64 adapted to receive the cartridge, which body portion opens upwardly so that the cartridge may be delivered through this opening to the chamber. At the rear portion of the cradle, overhanging flanges 65 and 66 are provided to hold the cartridge in the cradle until it has been moved forwardly to some extent by the bolt. Also adjacent its forward end the carrier is provided with a tail portion 61 to close the opening at the rear of the magazine when the carrier is lifted to transfer a cartridge to the receiver. A spring-pressed plunger t8, mounted in a portion of the receiver, engages the lower rear corner 69 of the carrier, tending to swing the carrier upwardly about its pivot 63. As shown more especially in Fig. 2, this upward movement is prevented when the bolt is in its forward breech-closing position by a cam surface it! formed on the bolt, which engages a lug H on the carrier disposed forwardly of its pivot. However, when the bolt is moved rearwardly and the cam surface disengages the lug H, the spring is then free to swing the forward end of the latter upwardly about itspivot and transfer a fresh cartridge into position to be moved into the chamber.

As shown more especially in Figs. 10 and 11, the body portion 64 of the carrier is provided with a slot I2, and a lifting finger 13 is pivoted to the carrier at M and designed to project through this slot under the force of a spring 15 mounted in the carrier and acting against a tail portion 16 of the finger 13. Movement of this finger may be limited by a stop 1'! formed on a part of the receiver, and adapted to engage the tail portion it when the lifting finger has been moved upwardly to its furthest extent, as shown in Fig. 4.

The operation of this cartridge transfer mechanism may now be described. As shown in Fig. 2, the gun is in cocked position ready to be discharged. When the cartridge i3 is fired, the bolt IE is forced rearwardly, thus moving the cam surface 10 from engagement with the lug H. The carrier 82 is then thrown upwardly about its pivot 63 by the spring-pressed plunger 68 to the position shown in Fig. 3, wherein the fresh cartridge l3 is in position to be forced into the chamber. It will be noted that the rear end of the cartridge is in engagement with the 6 overhanging flanges 65 and 66, and thus the lifting finger I3 is held downwardly against the tension of its spring i5 by the engagement of the forward end of this finger with the cartridge. The bolt is now moved forwardly by the bolt spring l8, and the forward end of the bolt engages the rear end of the cartridge, moving it forwardly out of engagement with the flanges 65 and 66. At this time the spring 15 moves the forward end of the lifting finger upwardly to a slight extent, thus moving the rear end of the cartridge upwardly so that the latter is in a correct position to enter the chamber. It will be noted that the lifting finger T? has a delayed action, and a slight movement under impulse of its spring independently of the carrier 62 in order to prope ly position the cartridge in front of the chamber.

When the bolt is returned to its forward position, shown in Fig. 2, the cam surface 10 reengages the lug l l thus moving the carrier downwardly into the position shown in Fig. 2. At this time the tail E5 of the lifting finger 13 engages the stop ll, and the lifting finger is moved in a reverse direction about its spring so that its forward end is lowered in the slot i2, thus permitting a fresh cartridge to slide from the magazine into the body portion or cradle of the carrier without interference.

A sear 8D is pivoted at 8! to the receiver, the sear engaging at its upper rear corner a bent 82 formed on the striker H, the sear being actuated by a trigger 83 of the usual form, pivoted to the receiver at 84. Pivoted to the forward end of the trigger at 85 is a dog 86 having a corner 81 engaging a bent 88 on the sear to move the latter downwardly about its pivot 8| out of engagement with the bent 82 of the striker when the trigger is pulled.

Usually the trigger will be pulled rearwardly a sufhcient distance to disengage the members 87 and 88, so that the sear 89 will be free immediately after it is released to move upwardly again and engage the bent 82 of the striker when the latter is carried rearwardly with the hammer after discharge. However, this disengagement is insured by a lug 89 at the upper end of the connector member 86, which lug is engaged by a portion 99 on the striker ll, so that, as the striker reaches its forward position to discharge the shell, the connecting member 86 will be moved about its pivot 85 and disengaged from the sear 80, thus permitting the latter to be moved upwardly or in a counterclockwise direction by its spring Hi. The member 86 is normally held in engagement with the sear by a spring-pressed plunger 92 carried by the trigger 83.

The striker spring, as shown in Fig. 9, acts at its front end against a headed pin 95, slidably associated with the striker I! and projecting forwardly a slight distance from the front end of the striker, to engage the shoulder 98 formed on the bolt adjacent the firing pin it when the striker is in its forward position. It will thus be seen that the tension of the spring 22, after the gun has been discharged and the striker is in its forward position, is borne by the pin 95 and not by the striker itself. Therefore, when the parts are in this position the striker will have slight play to and fro, which permits the firing pin to assume a retracted position out of engagement with a cartridge in the chamber. It will, of course, be understood that when the gun is discharged the inertia of the forward movement of the striker under impulse of the spring 22 will cause the striker to drive forwardly against the shoulder 96, as the pin 95 is slidably mounted in the striker. The impact of the striker, however, against this shoulder will cause it to return slightly, to the position shown in Fig. 9, thus also permitting the firing pin It: to return from its extreme forward position, so that its front end is flush with the adjacent portion of the bolt, as shown in this figure.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

1. A firearm comprising a receiver, a bolt reciprocably mounted therein longitudinally of the receiver, said receiver having a longitudinally extending slot in the wall thereof, a plug removably engaged with the bolt, a handle pivoted to the plug to swing in a plane transverse to the movement of the bolt and means on the handle to engage with a part of the slot and restrain the bolt against longitudinal movement.

2. A firearm comprising a receiver, a bolt reciprocably mounted therein longitudinally of the receiver, said receiver having a longitudinally extending slot in the wall thereof, a plug removably engaged with the bolt, a handle pivoted to the plug to swing in a plane transverse to the movement of the bolt, said plug being disposed in a recess in the bolt and normally retained therein by engagement of the handle with the edges of the slot and means on the handle to engage with a part of the slot and restrain the bolt against longitudinal movement.

3. A firearm comprising a receiver, a bolt reciprocably mounted therein longitudinally of the receiver, said receiver having a longitudinally extending slot in the wall thereof, a plug removably engaged with the bolt, a handle pivoted to the plug to swing in a plane transverse to the movement of the bolt, means on said handle to engage with a part of the slot and restrain the bolt against longitudinal movement said plug being disposed in a recess in the bolt and normally retained therein by engagement of the handle with the edges of the slot, and said slot having an enlarged portion permitting detachment of the handle and plug from the bolt when the handle is moved to a position opposite the enlarged portion.

4. A firearm comprising a receiver, a bolt reciprocably mounted therein, said receiver having a longitudinally extending slot in the wall thereof, a plug removably engaged with the bolt, a handle pivoted to the plug to swing in a plane transverse to the movement of the bolt, said plug being disposed in a recess in the bolt and normally retained therein by engagement of the handle with the edges of the slot, a, bumper closing the rear end of the receiver, interengageab-le means on the rear end of the bolt and the front end of the bumper for connecting the bumper and bolt together upon movement of the bolt to its rearmost position, whereby the bolt may be removed from the receiver by removal of the bumper therefrom.

' ROBERT L. JENKINSON.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS Great Britain Jan. 2'7, 1922 

